PAGE TOP

Figure 1. Results in acute study of 8 patients. (Ubutaka S, Ritter P) Click to enlarge

Theoretically, synchronous bi-ventricular pacing with the LV electrode placed at the base of the heart could counteract the reverse activation sequence induced by the right ventricular (RV) pacing. The presence of fibrous tissue due to the underlying diseases causes heterogeneity of the transmission of the heart excitation. Three types of asynchronies result from this heterogeneity, AV, intraventricular and interventricular. The goal of pacing therapy is to normalize these asynchronies. In an acute study of 8 patients, bi-ventricular pacing was associated with significant improvements from baseline in cardiac index, V-wave and PCWP (Figure 1). No statistically significant change was observed with RV pacing in RV apex and RVOT. But with Bi-ventricular pacing, there was a significant change in the RV apex-LV and RVOT-LV leading to a change in the cardiac index. Bi-ventricular pacing improved the hemodynamics in 7 patients, while no change was seen in one patient, stated Satoshi Ubutaka, MD, of Jichi Medical School. The mean age of the patients was 66 years, male 7, LVEF 22%, NYHA class IV 8, and QRS duration 200 ms (120-240 ms).

Figure 2. Results in 50 patients receiving chronic bi-ventricular pacing. (Ubutaka S, Ritter P) Click to enlarge

An evaluation of bi-ventricular pacing as a supplemental treatment for refractory heart failure was also performed by this group. This long-term study (1994-1997) of 50 patients who received chronic bi-ventricular pacing showed a consistent decrease in NYHA class, implying an improvement in quality of life (Figure 2). The average follow-up was 13 months and the average NYHA class was 2.3. There were 17 deaths (11 heart failure, 4 sudden cardiac death, 2 non-cardiac). Bi-ventricular pacing served as a bridge to transplant for 3 patients. IVD shortening was seen in the patients with bi-ventricular pacing compared to RV pacing (19 vs 54 ms), showing a change in interventricular delay. No significant change was seen in the intraventricular delay. The mean age was 68 years, male 47, NYHA class III 14, NYHA class IV 36 patients.

PAGE TOP

Figure 3. Survival by etiology of heart failure in patients who underwent partial left ventriculectomy. Click to enlarge

The underlying disease was dilated cardiomyopathy (DCM) in 92%, valvular 4.2%, dilated hypertrophic cardiomyopathy (DHCM) 1.4% and other in 2.4%. In terms of survival by etiology, no significant difference was observed, although it was somewhat lower in DCM and valvular disease than in coronary artery disease (Figure 3). In the registry, 82% were male, and 28% > age 50years, 32% > age 60 years and 17% > 65 years. Survival was better in those < 60 years, Fewer than 1 in 4 patients who underwent emergency PLV survived. Long-term prognosis was poor with an LV mass > 400 g. An indication for transplantation was associated with better survival compared to no indication. Survival was better in institutions that had performed more than 5 cases and even greater in those that had performed more than 10 cases. A learning curve for performing PLV is indicated by the improved survival after 1999. In summary, patient risk factors are age> 65 years, NYHA IV, % FS < 5%, emergency PLV, heart failure duration > 9 yrs and no indication for transplantation.

PAGE TOP

Figure 4. The duration of LV-VAS support in the study population. Click to enlarge

Of the 35 patients on VAS, 4 were weaned (3 discharge, 1 death), 16 died on VAS (2 in < 30 days, 10 candidates for transplant), 7 received a transplant, and 8 continue VAS. The average duration of assist was 224 days, with a range of 7-668 days (Figure 4). The major causes of death are infection, cerebral embolism and bleeding. Regarding heart transplantation, 5 of the 6 cases at the National Cardiovascular Center had been on LVAS. The number of days waiting for a transplant ranged from 29 to 628 days. Three of the 6 patients have returned to work and 3 remain in hospital. The bicaval approach was used in 5 and the Lower-Shumway in one. There have been no serious complications or rejections to date. Nakatani concluded that LVAS and heart transplant are optimal options for end stage heart failure, and that LV-LVAS especially is a good bridge to transplant.

PAGE TOP